Balloon catheters include an elongate tubular body defining one or more lumens, with an inflatable balloon positioned at a distal end of the elongate tubular body. Balloon catheters provide minimally invasive means for treating various conditions. For example, angioplasty is a common procedure used to treat cardiovascular disease. During an angioplasty procedure, a medical device, such as a balloon catheter, may be percutaneously inserted, over a wire guide, into a vessel narrowed by stenosis. The balloon may be expanded at the stenosis to ultimately restore blood flow through the vessel. In some cases, a stent may be placed at the narrowed portion of the vessel, using the balloon catheter, to help keep the vessel open.
The elongate tubular body of a balloon catheter typically has multiple lumens, with one lumen being an inflation lumen for the balloon and another lumen serving as a wire guide lumen for advancing the balloon catheter over a wire guide. The elongate tubular body of one type of balloon catheter terminates just inside a proximal end of the balloon, and a smaller single lumen shaft is bonded to the distal end of the elongate tubular body and extends through to a distal end of the balloon. The single lumen shaft permits the balloon to be mounted distally and advanced over the wire guide without the wire guide scraping or puncturing the balloon. While the single lumen shaft improves pushability of the balloon catheter by increasing column strength, the presence of the single lumen shaft inside the balloon adds to the overall dimensions of the balloon. There exists a need for balloon catheters having lower profiles and, since the balloon section often represents the longest diameter of the device, decreasing the contribution of the single lumen shaft to the diameter is desirable.